Hi,

this problem made me so curious that I investigated a little bit more. I'm pretty sure I found a reason for the problem but not the details.

Look at these two snippets which rebuild IMHO the code path which is taken by the initial code examples:

#!/usr/bin/perl
use strict;
use warnings;
use 5.010;

use Data::Dumper;
use Math::BigFloat;

use bignum;

{
    no bignum;
    require Math::BigFloat;
    my $one = Math::BigFloat->new('2');
    print Dumper($one);
    print Dumper("$one");
}
[download]

What you get is:

$VAR1 = bless( {
                 'value' => [
                              2
                            ],
                 'sign' => '+'
               }, 'Math::BigInt' );
$VAR1 = '2';
[download]

Compare this to the output of the snippet:

#!/usr/bin/perl
use strict;
use warnings;
use 5.010;

use Data::Dumper;
use Math::BigFloat;

#use bignum;

{
#    no bignum;
    require Math::BigFloat;
    my $one = Math::BigFloat->new('2');
    print Dumper($one);
    print Dumper("$one");
}
[download]

which has the following output:

$VAR1 = bless( {
                 '_m' => [
                           2
                         ],
                 '_es' => '+',
                 '_e' => [
                           0
                         ],
                 'sign' => '+'
               }, 'Math::BigFloat' );
$VAR1 = '2';
[download]

Do you see the relevant difference? In the first case you get a Math::BigInt object, in the second case a Math::BigFloat object.

After that I'm pretty sure that the constructor of Math::BigFloat does have a problem together with the pragma bignum.

Probably it's worth to file a bug against Math::BigFloat or bignum (probably not so transparent as stated). I really don't know.

Back to the initial problem. Math::FixedPrecision inherits from Math::BigFloat and not from Math::BigInt. Besides the fact that Math::FixedPrecision uses old and depreciated features of Math::BigFloat and manipulates the internals of Math::BigFloat circumventing the API which is a total OO-mess, this intransparency is pretty sure the cause of the exception.

Regards
McA